ENDOCRINE SYSTEM

TWO GREAT CONTROLLING SYSTEMS

Nervous System . . . . . . . . . . . . . . . . Endocrine System

1) NERVOUS SYSTEM• Regulates activity via action potential

impulses ~ AP’s• Impulses carried by specific sensory or

motor neurons• Uses “synaptic communication” to

carry message• Targets specific cells ~ for specific

response• Response is immediate & usually short

lasting

2) ENDOCRINE SYSTEM• Controls cell activity by secreting hormones ~

EXCITE• Hormones = “Chemical Messengers”

Secreted into blood & transported throughout body

• Generalized Widespread Response ~ Adrenalin or GH

• Targeted specific cells: TSH or FSH• Diverse or very specific effects: Insulin ~ specific

Adrenaline ~ diverse • Response on target cells is delayed ~ due to

circulation • Delayed, prolonged or continuous response

ENDOCRINE SYSTEM ~ Controlling Spectrum

MAJOR processes controlled by hormone release

Reproduction TestosteroneEstrogenFollicle Stimulating HormoneLeutenizing HormoneOxytocin ~ “Post Pit”

Growth & Development

Growth Hormone & Thyroid Hormone

Body Defense Mechanisms

Corticosteroids ~ Cortisone ~ Anti-inflammatory

Anti-Stress

Corticosteroids ~ Gluconeogenesis

Electrolyte, Water & Nutrient Balance

Aldosterone ~ Na+ retention ~ water retention

Anti-Diuretic Hormone ~ ADH

Cell Metabolism & Energy Regulation

Insulin & Thyroid Hormone

Digestive Processes

TWO GLANDULAR SYSTEMS OF BODY

1. EXOCRINE GLANDS ~ Merocrine . . . Apocrine . . . Holocrine ~

< PUREST ------------------------------ MESSY >

Secreted onto body surfaces ~ via ducts Secretions are non-hormonalSecreted & ACT LOCALLY in a target area onlyDO NOT secrete into blood or lymphatics Can be large in size or extensive in numbers ~ millions

Examples of Exocrine Glands SecreteMucous Glands MucousSudoriferous Glands SweatSebaceous or Oil Glands SebumSalivary Glands SalivaMammary Glands MilkLiver BileEnteric Glands DigestionReproductive Glands Several

Pancreas ~ Both Exocrine & Endocrine

2. ENDOCRINE GLANDS

“Ductless Glands” ~ produce hormones ~ NO DUCTS

Secrete hormones most directly into blood

Surrounded by many capillaries ~ allows secretion into blood

Hormones travel through body ~ act on specific target organs

Can have a generalized effect or specific target effect

Effects can be short, prolonged or continuous lasting

Small Glands ~ very localized, & few in numbers ~ 12 groups

ENDOCRINE GLANDS

Pituitary Gland HeartPineal Gland Small IntestinesThyroid Gland KidneyParathyroid Gland PancreasThymus Gland Gonads (ovaries & testes )Adrenal Gland Hypothalamus

Other Specialized Cells can produce hormonesAdipose Tissue . . . .Tumors or cancer cells

CHEMISTRY OF HORMONES

Hormones ~ “chemical messengers” ~ “First Messengers”

Control other parts of body from where secreted

“Endocrine Communication” ~ NOT NEURAL

MOST Secreted into blood & circulatory system

Regulate functions of other cells somewhere else

Major Hormone Classifications

1.Amino Acid Hormones ~ MOST COMMON

Most hormones are globular proteins or peptides

2. Lipid HormonesSteroid Hormones ~ from cholesterol

Gonadal hormones ~ estrogen, testosterone

Adrenalcorticoids hormones ~ corticosteroids

Eicosanoids (eye cos an oids) Increase inflammation & cause swelling

NON-CIRCULATING hormones ~ act locally only

Released from most cell membranes & have

a highly localized response

Prostaglandins ~ most common

MECHANISM OF HORMONE ACTION

Hormones effect target cells ~ alter cell activityIncrease or decrease types & rates of cellular

processesUp-Regulation ~ increased sensitivity to

hormone effectsDown-Regulation ~ less sensitive to

hormone effectsActivity is very specific on a specific target cell

EG: Epinephrine causes blood vessel walls to contract

It will also cause an increase in heart rate

HORMONE EFFECTS ON TARGET CELLS

1. Change plasma membrane permeability2. Change electrical charge of plasma membranes3. Stimulate secretory activity of cells4. Stimulate mitosis & cell division5. Stimulate Enzyme Activation or Deactivation ~ MOST

COMMONForms NEW proteins within cellsAmino Acid Hormones ~ cAMP Second Messenger

6. Stimulate Gene Activation ~ COMMONLipid/Steroid Hormones ~ Form New Proteins

EXAMPLES ~ MECHANISMS OF HORMONE ACTION

AMINO-ACID HORMONES (“PEPTIDES”) ~ MOST COMMON Utilizes a Second Messenger System

Hormone ~ is the first messenger

Hormone CANNOT penetrate cell membrane ~ to big

Binds to “hormone receptor” site on target cell

Receptor binding ---> activates a “G-protein” --->which activates an effector enzyme

Effector Enzyme = Adenylate cyclaseAdenylate cyclase generates Second Messenger ~ cAMP

cAMP activates protein kinase - - -> form NEW PROTEINS inside cell

MANY reactions follow & cause specific cell activities

LIPID ~ STEROID HORMONES “from CHOLESTEROL”

Utilizes: Gene Activation ~ NO 2nd messenger system Smaller & lipid soluble ~ can penetrate cell membrane

Once inside target cells ~ gene activation occurs

DNA is “transcribed” to messenger RNA ~ mRNA

mRNA ~ stimulates production of NEW proteins

HORMONE TARGET CELL ACTIVATION & SPECIFICITY

Major hormones circulate in blood to all tissue

Specific hormones effect only specific tissue cells

Hormone Receptors ~ located on or in cellsTarget Cells have specific hormone receptors on cell membranes or inside target tissue that bind hormones

Receptor Binding is required for activity

SOME receptors are found only on/in SPECIFIC CELLS Example: ACTH stimulates only the adrenal cortex

SOME receptors are found on/in MOST BODY CELLSExample: Thyroxine stimulates most cells

Insulin affects all cells of body

Target Cell Activation Requirements

Adequate Hormone Blood Levels

Specific Receptor Binding Sites

Adequate Number of Receptors on or within cells

Specific Bonding Affinity between Hormone & Receptor

Any +/- Changes in any of the above results in: Endocrine Dysfunction Up Regulation OR

Down Regulation

ENDOCRINE DYSFUNCTION

Up-Regulation ~ Sensitization ~ StimulationOccurs when target cells form MORE receptors in response to hormone presence

Down-Regulation ~ Desensitization ~ InhibitionOccurs when prolonged exposure to high hormone levels causes LOSS of receptors

Desensitizes target cells resulting in lower activity

Hormones also STIMULATE or INHIBIT other hormonesEG: Estrogen stimulates Progesterone release

Progesterone antagonizes Estrogen action

DURATION OF HORMONAL ACTIVITY ~ “Half-Life”

Dependent on circulating blood levels of Hormone

1) Rate of Release into the blood

2) Speed of Inactivation & Removal from the body

Methods of Inactivation ~ Removal from body

1) Degradation by enzymes in target cells

2) Removed from blood via Kidney and Liver

3) Excreted in Urine or Feces

HALF-LIFE

Time required to reduce blood concentrations by 50%

Ranges from seconds to minutes to hours or longer

What is the Half-Life? . . . .If blood concentration is 20 units &

. . . . . 15 units remain after 7 minutes

. . . . . 10 units remain after 14 minutes = HALF-LIFE

. . . . . 5 units remain after 21 minutes

Endocrine Reflexes ~ CONTROL HORMONE RELEASE

Blood levels are precisely controlled for optimal effects

1) POSITIVE FEEDBACK MECHANISMAs hormone is released, target organ stimulates the release of more hormone . . . more . . . more . . . moreEG: Oxytocin ~ Childbirth

2) NEGATIVE FEEDBACK MECHANISM ~ MOST COMMONAs blood hormone levels rise, target organs inhibit further hormone release ~ on . . . off . . . on . . . off EG: thermostat in a houseEG: High blood sugar ---> insulin release --->

---> glucose uptake into cells ---> lower blood sugar

TYPES OF ENDOCRINE GLAND RELEASE STIMULI

Endocrine Gland Reflexes

Stimulate glands to produce & release hormones

1) Humoral Stimuli ~ ions & chemicals

2) Neural Stimuli ~ nerve impulses

3) Hormonal Stimuli ~ other hormones

HUMORAL STIMULI

Hormones secreted in direct response to changing blood levels of certain IONS & CHEMICALS

Examples: Low blood Ca+ ---> parathyroid gland to secrete parathyroid hormone (PTH) ---> higher blood Ca+ --->

reduced secretion of PTH

High blood sugar ---> pancreas to secrete insulin --->

lowering of blood sugar

NEURAL STIMULINerve IMPULSES (AP’s) stimulate

hormone release

EG: Stress ---> Sympathetic NS activation ---> adrenal medulla secretes catecholamines

Adrenalin ~ norepinephrine & epinephrine

HORMONAL “TROPIC” STIMULI ~ COMMON

Occurs when an endocrine gland releases hormones that stimulate OTHER endocrine glands to release hormones

Hypothalamus ~ Highest level of endocrine controlIntegrates activities of endocrine & nervous systemProduces Hormones that regulates Pituitary Gland

Pituitary produces other hormones that regulate OTHER glandsHypothalamic-Pituitary -Target Endocrine Gland

Feedback Loop

SEVERAL Hypothalamus “Regulating” Hormones

Thyrotropic Releasing Hormone (TRH)Stimulates release of TSH from Ant. PituitaryTSH stimulatesThyroid Hormone from Thyroid

Corticotropin Releasing Hormone (CRH)Stimulates release of ACTH from Ant. PituitaryStimulates Adrenal Hormones from Adrenals

Gonadortophin Releasing Hormone (GnRH)Stimulates release of FSH & LH from Ant. Pit.Stimulates Testosterone, Estrogen & Progesterone from Gonad

12 MAJOR ENDOCRINE ORGANS

12 MAJOR ENDOCRINE ORGANS

PITUITARY GLANDAlso called the “Hypophysis” ~ “Master Gland of Body”Protected by sella turcica of the sphenoid bone

At the base of the brain ~ not a part of nervous system

Infundibulum ~ “stalk” ~ connects pituitary to hypothalamus

Two lobes: Anterior Pituitary ~ “adenohypophysis”

Posterior Pituitary ~ “neurohypophysis”

HYPOTHALAMUSLocated above the brain stem ~ in diencephalon

Controls Autonomic Nervous System

1. Controls emotion ~ rage, fear, anger, pleasure

2. Body temperature regulation3. Food intake regulation ~ appetite4. Water balance & thirst regulation

Controls Endocrine System Produces Hormones that “regulate” the

Anterior Pituitary

Produces two hormones released by the Posterior Pituitary

ADH . . . . . . Oxytocin

HYPOTHALAMUSProduces “Releasing & Inhibiting” Regulating Hormones

Carried via “Hypophyseal Portal System” to Ant. Pit.

Vascular connection ~ hypothalamus & Ant. Pit

“Releasing” Hormones

Stimulate secretion of Anterior Pituitary Hormones

“Inhibiting” HormonesInhibit release of Anterior Pituitary Hormones

Produces 2 “Neuro-Hormones” for Posterior Pituitary

Paraventricular Nucleus ----> Oxytocin

Supraoptic Nucleus ----> Anti-diuretic Hormone ~ ADH

Carried via “Hypothalamic-Hypophyseal Tract” by axons to posterior pituitary

Neuro-Hormones are secreted by Posterior Pituitary

“Hypophyseal Portal System”

Vascular connection ~ hypothalamus & anterior pituitary

“Hypothalamic-Hypophyseal Tract”

Neural connection ~ hypothalamus & posterior pituitary

ANTERIOR PITUITARY ~ “Master Endocrine Gland”

ANTERIOR PITUITARY ~ “Master Endocrine Gland”

Anterior Lobe ~ “Adenohypophysis”Controlled by the hypothalamus via regulating hormones

Hypophyseal Portal System Fenestrated Capillaries ~ vascular bed connections

Allows hypothalamic hormones to circulate through the anterior pituitary

Regulating Hormones ~ regulate the secretions of other hormones from anterior pituitary gland

Secretes 6 major hormones ~ ALL ARE PROTEINS

Instantaneous Response ~ NO storage in Anterior Pit.

Tropic Hormones: Hormonal StimuliRegulate the secretory action of OTHER endocrine glands to release other hormones

TSH Thyroid Stimulating Hormone

ACTH Adrenal Corticotropic Hormone FSH Follicle Stimulating Hormone

LH Leutenizing Hormone

Non-tropic Hormones: Effects NON-ENDOCRINE glands

GH Growth Hormone

PRL Prolactin

ANTERIOR PITUITARY - “TROPIC”

HORMONES THYROID STIMULATING HORMONE ~

TSH

TRH ~ Thyrotropin Releasing Hormone - Hypothalamus Stimulates release of TSH from Anterior Pituitary

TSH (tropic) ~ stimulates Thyroid Gland to secrete Thyroid Hormone

Negative Feedback “Shut Off” MechanismRising blood levels of TH “shuts off” the

Hypothalamus & Anterior Pituitary to block further TSH release

Factors releasing TRH from Hypothalamus1. Increased Energy Demands2. Need to raise metabolic rate3. Need to produce & release heat

EG: PregnancyCold temperaturesExerciseFever

ADRENOCORTICOTROPIC HORMONE ~ ACTH

CRH ~ Corticotropin Releasing Hormone - Hypothalamus Stimulates release of ACTH from Anterior Pituitary

ACTH tropic action: stimulates the adrenal cortex to release several other hormones:

1) Gluco-corticoids ~ corticosteroids ~ mostly

2) Gonad-ocorticoids ~ androgens ~ small amount

3) Mineralo-cortacoids ~ aldosterone

Negative Feedback “Shut Off” MechanismRising blood levels of “corticoids” cause Anterior Pituitary & Hypothalamus to block further CRH release

Factors stimulating CRH release: feverhypoglycemiastressdehydration shock blood loss low blood pressure

GONADOTROPINS

FSH ~ Follicle Stimulating Hormone

LH ~ Leuteinizing Hormone

GnRH ~ gonadotropin releasing hormone from Hypothalamus Stimulates release of FSH or LH from Anterior Pituitary

FSH and LH ~ action is tropic Stimulate gonad activity ~ ovaries & testes ~ at puberty

FSH ~ stimulates sperm & egg production

LH ~ cause ovarian follicle maturation & ovulation

~ causes release of Gonadal HormonesEstrogen ~ Female ~ controls menstrual

cycle Progesterone ~ Female ~ maintains

pregnancyTestosterone ~ Male Testicular

Hormone

Negative Feedback “Shut-Off” Mechanism

Rising blood levels of gonad hormones causes the Hypothalamus to block GnRH release, & inhibits FSH & LH release from Anterior Pituitary

ANTERIOR PITUITARY - “NON-TROPIC” HORMONES

GROWTH HORMONE ~ GH ~ “Somatotropin”

“Anabolic Hormone” ~ stimulates most body cells to increase in size and divide

GH targets bones & skeletal musclesStimulates epiphyseal plate & long bone growthIncreases skeletal muscle mass

“Insulin-growth factor” ~ Somatomedins ~ enhance GHProtein produced in liver & muscle stimulate growth

GH Actions

1) Stimulates protein synthesis ~ anabolic ~ muscles

2) Stimulates cartilage & bone development3) Stimulates fats for energy ~ increases

glucose4) Converts glucose to glycogen stores for

future5) Causes a “diabetogenic” effect Causes glycogen breakdown & release of

glucose into blood causing ↑ blood sugar

GROWTH HORMONE ~ GH ~ “Somatotropin”

Secretion of GH ~ NOT a feedback mechanism

GHRH – GH Releasing Hormone

Hypothalamic hormone - stimulates release of GH

GHIH – GH Inhibiting Hormone – Somatostatin

Hypothalamic hormone - inhibits release of GH

PROLACTIN ~ PRLPRL has direct action on non-endocrine mammary cells; Stimulates milk production by breast (not release)

PRL is controlled by Hypothalamus PRH ~ Prolactin “Releasing” Hormone = seratonin; Causes prolactin release

from Ant. Pituitary

PIH ~ Prolactin “Inhibiting” Hormone = dopamine; Prevents prolactin secretion from Ant. Pituitary

PRL Levels fluctuates in females with ESTROGEN

Low Estrogen stimulates PIH ---> LESS Prolactin

High Estrogen levels stimulates PRH ---> MORE PRL Menstruation ~ HIGH Estrogen ---> PRH ---> MORE PRL

Breast swelling & tenderness ~ temporaryGenerally NO milk production

Pregnancy ~ cause HIGH levels of PRH near termInfant Suckling ~ stimulates PRH ---> MORE PRL

PRL Hyper-Secretion ~ occurs in nursing mothersPRL Hypo-Secretion – only occurs in heavy nursers

POSTERIOR PITUITARY

Neurohypophysis ~ Posterior Lobe + Infundibulum Neural Portion (axons) is an extension of the

Hypothalamus; Stores two “neurohormones” produced in the hypothalamus

1) Oxytocin ~ effects uterus & mammaries2) Antidiuretic Hormone ~ ADH ~ retains water

Neurohormones released into capillary beds of posterior pituitary in response to neural stimulation ~ Humoral

OXYTOCIN ~ “Post pit”

PRODUCED in hypothalamus ~ Paraventricular NucleiUterus & Cervic Stretching during childbirth stimulatesReleased from Posterior Pituitary ~ Positive Feedback

Effects: 1) Stimulates uterus muscle contraction 2) Stimulates mammaries to release & “let-

down” 3) Stimulates sexual arousal & orgasm 4) Promotes nurturing & cuddling ~ “nesting”

Highest Concentrations ~ during childbirth & nursing Synthetic Drug ~ induces labor & stimulates milk “letdown”

ANTIDIURETIC HORMONE ~ ADHWhat is “Diuresis”??? = Excess Urine production

ADH = “Anti-Urine Hormone” = AGAINST DIURESIS

“Vasopressin” ~ causes vasoconstriction & elevates Blood Pressure

PRODUCED in hypothalamus ~ Supra Otic Nuclei

Stimulated by need to retain fluidsDehydration ~ Excess sweating ~ no fluid intakeHemorrhage ~ Blood LossLow blood pressure & Shock

Released from Posterior Pituitary into blood

Effects:1) Targets Kidneys ----> Water Retention 2) Prevents urine formation ----> water

retention; Reabsorbs water back into blood in kidneys

3) Increases blood pressure ~ due to vasoconstriction & retained fluid volume in blood

Controlled by Negative feedback “Shut-Off” MechanismInhibited by High Blood Volume . . . High Blood Pressure. . . Fluid Retention . . . Over-Hydration

ADH INHIBITORS ~ BLOCK ADH ~ “Diuretics”Stimulate urine production & fluid loss

Results in copious urine production & outputFlushes water from body ~ DehydrationMorning after dry mouth & intense thirst ~ drinkingDecreases Blood Fluid Volume ----> lowers BP

Examples of ADH Inhibitors ~ ALL act as DIURETICSDrinking excessive fluid & Alcoholic

beverages Diuretic Drugs ~ Diet Pills ~ DexetreneHypertension Drugs ~ to lower blood pressure

THYROID GLANDLargest “pure” endocrine ONLY gland in

body ~ “Butterfly” On the trachea ... Anterior throat area … below the

larynx

Two lateral lobes connected by a median isthmus

Blood Supply ~ via thyroid artery off common carotid artery

Extremely vascular ~ Surgery very difficult

Internal Thyroid Tissue Histology

1. Follicular Cells - spherical cells ~ surround lumen; Produce thyroglobulin ~ glycoprotein

2. Lumen of follicle ~ stores colloidColloid = thyroglobulin + attached iodine

“Iodinated Thyroglobulin” Precursor for Thyroid Hormone ~ T3 or T4

3. Parafollicular Cells ~ around & between the follicle Endocrine cells that produce calcitoninCalcitonin ~ lowers blood calcium levels

Thyroid Gland is Unique . . . Only endocrine gland that stores

hormones in large quantities ~ in colloid THYROID HORMONE ~ TH

“Body’s major “metabolic hormone”

Thyroid Hormone is two Iodine containing hormones

T4 Thyroxine ~ STORED FORM ~ NOT ACTIVE

90% of TH ~ secreted by follicle cells

T3 Triiodothyronine ~ NOT stored ~ “ACTIVE”

Formed at target tissues by conversion of

T4 (STORED) > > > T3 (“Active)

Thyroid Hormone affects most cells except:Brain ... Spleen ... Testes ... Uterus ... Thyroid

Effects of Thyroid Hormone

1. Stimulates carbohydrate, lipid & protein metabolismGlucose & fat catabolism ~ energy producedProtein & cholesterol synthesis ~ growth

2. Increases basal metabolic rate & O2 consumptionCalorigenic Effect ~ burn calories ~ body heatPromotes normal oxygen use by cells

3. Regulates tissue growth, development, & function

Thyroid Hormone Release ~ “Negative Feedback”

1.Falling blood levels of thyroxin (T4) ----> Hypothalamus to release thyrotropic releasing hormone (TRH)

2.TRH ----> anterior pituitary to release thyroid stimulating hormone (TSH) into blood

3.TSH ----> Thyroid to release thyroxin (T4 & T3) into blood

4.Thyroxin (T4 & T3) is carried to target organ receptors

T3 is formed at the target tissue by conversion of T4 5.T3 or T4 actively exert effects on the target

tissue 6.Rising blood levels of T3/T4 “shuts off”

hypothalamus --> inhibits release of TRH (hypothalamus) & TSH (Ant. Pit)

Factors Triggering TSH release from anterior pituitary:Any conditions increasing body energy requirements

Pregnancy ~ requires energy for fetus

Prolonged Cold ~ requires body heat

Extensive Exercise ~ requires energy & O2

Factors Inhibiting TSH release:

Somatostatin ~ growth hormone inhibitor ~ less energy

Rising levels of glucocorticoids ~ high blood sugar

High blood iodine concentration ~ Stimulates excess TH

----> shuts off Hypothalamus

THYROID GLAND HORMONES

CALCITONIN Produced by parafollicular cells of ThyroidProtein hormone ~ lowers blood Ca++

Direct antagonist to parathyroid hormone

Mode of Action:1) Targets skeletal tissue & bone2) Inhibits osteoclast activity & bone resorption3. Inhibits release of ionic calcium from bone4. Stimulates calcium uptake into bone

Stimulates osteoblast activity in bone

Calcitonin Secretion Stimuli:

Cycles up & down with parathryroid hormone

Excessive blood levels of calcium -----> “calcitonin” release ~ to lower blood calcium

Part of “negative feedback” system with “parathyroid hormone” from parathyroid gland

PARATHYROID GLAND

Very tiny ~ on posterior side of thyroid gland . . . two pairs, one on each side ~ numbers can vary

Function is antagonistic to thyroid gland

Thyroid ~ calcitonin lowers blood Ca++

Parathyroid ~ parathyroid

hormone raises

blood Ca++

Histology of Parathyroid Tissue

1. Chief Cells – round and dark stained

Produce “Parathyroid Hormone” ~ PTH

2. Oxyphil Cells – function unknown

3. Capillaries - extensive network

Parathyroid Hormone ~ PTH ~ “Parathormone”

Most important hormone controlling blood calcium levels

PTH Secretion & Release StimuliLow blood calcium levels (hypo-calcemia) ----> Stimulate Parathyroid Hormone release

High blood calcium levels (hyper-calcemia) ----> inhibits Parathyroid Hormone release

Main Effect of PTH ~ increases blood calcium ion levels

Direct antagonist to calcitonin (lowers blood Ca++ )

Parathyroid Hormone ~ PTH Blood Calcium Balance ~ needed for many body

functions:Nerve impulse transmission

Muscle contraction Blood clotting

Bone development & maintenance

Mode of Action ~ Parathyroid Hormone 1. Skeletal Tissue ~ stimulates bone cells (osteoclasts) to release calcium from bone into blood2. Kidney ~ enhances reabsorption of calcium into

blood3. Kidney ~ activates Vitamin D -----> increases

intestinal absorption of Ca++

ADRENAL GLAND ~ the “Stress Gland”

Paired ~ pyramid shaped ~ On top of each kidney

“suprarenal glands” ~ above the kidney

Each adrenal gland ~ two distinct glands in oneAdrenal Medulla – smaller interior part

Adrenal Cortex – larger portion surrounds medulla

Each produces different types of hormones

BOTH are stimulated in response to stressful situations

Adrenal Cortex

Adrenal CortexAdrenal Cortex Hormones Function Zona glomerulosa Mineralocorticoids

(Aldosterone) Mineral & water balance Na+ retention

Zona fasciculata Gluco-corticoids

Cortico-steroids (Cortisone, Cortisol)

Gluconeogenesis

Energy Metabolism

Anti-inflammatory

Immune Supression

Zona reticularis Gonado-corticoids

(Androgen) Sex Hormones

Adrenal Medulla Hormones Function

Adrenal Medulla

Hormones Catecholamines Adrenalin

Epinephrine

Nor-Epinephrine

Increases BP

Increases HR

Dilates Bronchioles

Decrease Peristalsis

ADRENAL CORTEX

MINERALOCORTICOIDS ~ AldosteroneAldosterone ~ 95% of mineralo-corticoidsProduced in Zona GlomerulosaRegulate Na+ concentration in body fluids & blood

Retains Na+ ~ most vital ion causing fluid retention

Sodium retention causes fluid retention

~ EDEMA Retains water & fluid ~ same

effect as ADH

Aldosterone EffectsReduces Na+ excretion from body

Retains Na+ from urine in kidney tubules Retains Na+ from perspiration & saliva

Water follows sodium > > > fluid retention

Aldosterone Secretion Stimuli Anything Requiring Fluid Retention

Decreased Na+ blood levels Decreased blood volume ShockDecreased blood pressure Dehydration

Blood Loss

Aldosterone Release MechanismsRenin-Angiotensin-Aldosterone Mechanism ~ MAJOR

1. Low blood pressure or lost blood volume is sensed by juxtaglomerular apparatus in kidney

2. Kidney releases Renin into blood

3. Renin ----> Angiotensin I in blood Angiotensin I ----> Angiotensin II in blood

4. Angiotensin II stimulates adrenal cortex to release Aldosterone which ----> Na+ retention in the kidney

5. Na+ & water retained in the blood ---->increasing blood volume & blood pressure ~ decreased urine

Other Aldosterone Release Mechanisms ~ MINOR

ACTH ~ adrenocorticotropic hormoneSevere stress ----> hypothalamus secretes corticotropin releasing hormone ----> anterior pituitary to secrete ACTH ----> release of Aldosterone ----> Sodium Retention Effects

Atrial Natriuretic Peptide ~ ANP ~ inhibits aldosteroneIncreased blood pressures stimulates heart to release ANP which inhibits the renin-angiotensin mechanism ----> Na+ & water excretion & lower blood pressure

ADRENAL CORTEX HORMONES

GLUCOCORTICOIDS ~ “Cortisone”

Produced in Zona Fasciculata

Cortisol ~ hydrocortisone ~ most significant

Cortisone ~ produced in liver from cortisol

Glucocorticoid Effects ~ MANY1. Reduces stress ~ prepares body for crisis

Thru gluconeogenesis & glycogenoslysis“Diabetogenic” Effect ~ ↑ blood sugar

Converts glycogen to glucose Converts fats to glucose

2. Stimulates protein breakdown to amino acids 3. Anti-Inflammatory ~ reduces swelling ~

“cortisone”4. Supresses immunity ~ organ transplants5. Stimulates appetite ~ “cortisol”6. Used as a synthetic drug ~ allergy & inflammation

Cortisone . . . Prednisone . . . Hydrocortisone

Glucocorticoid Hormone Release - stimulated by stress

Physical & Emotional trauma . . . Hemorrhage . . . Illness

Severe stress ----> hypothalamus secretes corticotropin releasing hormone ----> anterior pituitary to secrete ACTH ----> stimulates release of Cortisol & Cortisone

GONADOCORTICOIDS ~ Sex Hormones

Produced in Zona Reticularis of Adrenal Cortex

Mainly Androgen ~ male sex hormone ~ Testosterone Some Estrogen ~ female sex hormone

Lower concentrations than ovaries & testis

Significant levels ~ up to puberty ~ between ages of 7-13

Hyper-secretion could cause masculinization in childrenEarly hair ~ beardDeeper voiceSexual aggressiveness

ADRENAL MEDULLA

Centrally located in adrenal gland ~ Smaller portion

Secretes CATECHOLAMINES - effects Sympathetic NS

80% Epinephrine & 20% Norepinephrine = Adrenaline

Release: Stress stimulates the sympathetic nervous system ~ prepares body for crisis

Immediate Response ~ “short acting”

Sympathomimetic Effects:Blood sugar risesHeart beats fasterBlood pressure increasesBronchioles dilate ~ more airPupils dilate ~ more light Digestion & Peristalsis Slows

Visceral Vasodilation & Peripheral Vasoconstriction diverts Blood to where it is needed

From skin & digestive organs to brain, heart & skeletal muscle

MAJOR ENDOCRINE ORGANS

PANCREAS

Large, soft, triangular - posterior to

stomach

Mixed gland: Endocrine &

Exocrine function

Exocrine Pancreas ~ 99%

Ascinar Cells ~ epithelial cells ~ 99% of gland

Digestive enzymes ducted into small intestine

Amylase ~ carbohydrate breakdown

Lipase ~ lipid breakdown

Protease ~ protein breakdown

Endocrine Pancreas ~ 1%Islets of Langerhans~ 1% of Gland

Tiny island cluster cells among Ascinar cells

Alpha cells ~ secrete Glucagon Beta cells ~ secrete Insulin

Both regulate blood glucose ~ effects are opposite

Glucagon ~ raises blood glucose ~ hyper-glycemic

Insulin ~ lowers blood glucose ~ hypo-glycemic

GLUCAGON

Protein produced in alpha cells ~ (islets of langerhans)

Potent hyper-glycemic effects: Blood Sugar

Glucagon Secretion ~ Humoral Stimuli

Stimulated by: Falling blood sugar levels

Inhibited by: Rising blood sugar levels

Effects of Glucagon ~ Glucagon Blood Sugar

1. Breaks down glycogen to glucose ~ glycogenolysis

2. Stimulates Glucose Synthesis from fats & amino acids…. “gluconeogenesis”

3. Stimulates Release of glucose from liver into blood blood sugar

4. Stimulates breakdown of protein to Amino Acids…. “Catabolic Effect”

INSULINSmall protein ~ made in beta cells ~ islets of

langerhans

Potent hypoglycemic effects Blood Sugar

Insulin Secretion ~ Humoral Stimuli Stimulated by: Rising blood sugar levels

Eating a mealOther hyperglycemic hormones

Glucagon Growth Hormone

ThyroxinGlucocorticoids

AdrenalinInhibited by: Lower blood sugar levels

Major Effects of Insulin ~ opposite of glucagon

1. Enhances glucose uptake & utilization by all cells

2. Stimulates glycogen storage in muscle & liverInhibits Glycogenolysis ~ lowers blood sugar

3. Inhibits conversion of fats & amino acids to glucoseInhibits Gluconeogenesis ~ lowers blood

sugar

4. Stimulates protein synthesis from amino acids “Anabolic Effect”

5. Stimulates Glucose conversion to fat for storage

OTHER ENDOCRINE ORGANS

PINEAL GLAND

Tiny pine cone shaped . . . in epithalamus of diencephalon

Soft tissue landmark ~ pineal sand/calcium for brain X-rays

PINEAL GLAND

Endocrine function is a mystery ~ biorythms/sleep-wake/temp

MELATONIN ~ pineal gland hormone

* Peak levels at night make us

drowsy

* Stimulation of pineal gland related

to visual light

* Influences sleep/wake cycle, body

temperature, & appetite ~ biorythms

THYMUS

• Large in infants & children ~ provides immunity in children

• Located deep to sternum in upper thorax at base of heart

• Becomes adipose tissue & connective tissue with age ~ scars

THYMUS

Secretes hormones: Thymopoitens

Thymosins

Effect: Normal development of T-lymphocytes ~ T-cells

Important in the immune response ~ infant & young

GONADS

Male Gonads ~ Testis

Female Gonads ~ Ovaries

Produce more sex hormones than the adrenal cortex . . .

Release regulated by FSH & LH gonadotropins from pituitary

OVARIES

• Two oval shaped . . . Posterior abdominal cavity

• Produce ova or eggs for fertilization

• Produce female ovarian hormones

OVARIES

ESTROGEN ~ release influenced by FSHReleased from follicle cells of ovariesCauses maturation of reproductive organsFemale secondary sex characteristics ~

pubertyMenstrual cycle ~ uterus cyclic changes

PROGESTERONE ~ release influenced by LHReleased from corpus luteum ~ old follicleMaintains pregnancy ~ secreted for months

TESTES

• Two ~ Located in “extra-abdominal” sac ~ scrotum

• Produce sperm (influenced by FSH) & male sex hormone

TESTES

Testicular Hormones ~ male hormone ~ androgens

TESTOSTERONE ~ release influenced by LH

Produced in interstitial cells of testis

Causes maturation of male reproductive organs

Male secondary sex characteristics & sex drive

Necessary for normal sperm production

OTHER HORMONE PRODUCING STRUCTURESNot really endocrine glands . . . but have

other endocrine cellsHEART

Atrial wall stretched by excess fluid volume & pressure

Releases: Atrial Natriuretic Peptide ~ ANP

Effects of ANP:Inhibits Aldosterone release by adrenal cortexInhibits sodium & fluid retentionReduces blood volume & lowers blood pressure

GASTROINTESTINAL TRACT (GIT)

ORGANS Several Hormones Released to aid digestion

Hormone Source Target Organ & Effect

Gastrin Stomach Stomach HCL Release

Serotonin Stomach Stomach Contraction

Intestinal gastrin Duodenum Inhibits stomach HCL

Slows GI Motility

Secretin Duodenum Inhibits gastric secretions

Release bicarbonate from pancrease & liver

Cholecystokinin Duodenum Pancreatic juices & bile

Amylase~CHO

Lipase~Fats

Protease~Proteins

KIDNEY

Erythropoietin ~ EPOInfluences bone marrow to produce more

RBC’s

ReninStimulates Aldosterone

SKIN

CholicalciferolPrecursor to Vitamin D3

Intestine absorb of Ca++

HORMONES INVOLVED IN GROWTH

Involves coordination of several endocrine organsImportant Hormones: Growth Hormone

Thyroid HormoneInsulinParathyroid HormoneCalcitrol ~ for Ca++

absorption Reproductive

Hormones

HORMONES INVOLVED IN AGING

Few functional changes with age ~ most work until death

Major changes involve decline of reproductive hormones

Decline in Growth Hormone

Other changes due to disease processes ~ i.e., diabetes

HORMONES INVOLVED IN STRESS

Stress Activates the General Adaptation Syndrome

Involves: Hypothalamus . . . Adrenal Gland . . . Organs

Alarm Phase

~ immediate fight or flight ~ adrenalineNeural Stimulation ~ immediate ~ short acting

Catecholamines: Epinephrine & Nor-epinephrine

Sympathetic Effects: ↑ BP . . . ↑ HR . . . ↓

Digestion